Polyethylene sleeving is a tubular film of low-density polyethylene slipped over and snugly fitted to a pipe at the time of laying. It is used to supplement the basic pipe coating (metallic zinc + bituminous paint) in certain cases of highly corrosive soils, or in the presence of stray currents.
To make the installation easier the polyethylene sleeving is delivered precut for pipe sizes DN 60 to 600.
The polyethylene film is made of low-density polyethylene (LDPE) in tubular film and is slipped over and snugly fitted to a pipe by means of:
- adhesive plastic tape at each end,
- intermediate tie fasteners.
The technique using a barrel sleeve (applied outside the trench) and separate joint sleeve (applied in the trench after jointing) is preferable to the technique using a single sleeve (socket and barrel) since it provides better protection.
Polyethylene sleeving supplements the zinc coating. Its protective mechanism consists of insulating the pipes from corrosive soil (suppression of electrochemical
cells) and from the ingress of stray currents. Even if a small amount of water infiltrates the sleeving it still provides protection by substituting a homogeneous environment (ground water) with a heterogeneous environment (soil).
PAM recommends the use of this additional protection in corrosive soils, such as:
- low resistivity soils (an indication of high corrosion),
- stray current areas,
- soils where analysis shows high chloride or sulfate contents, or bacterial activity.
It can be applied after the trench has been opened if the local conditions justify its use. Use of the Polyethylene sleeving is, generally, not necessary for NATURAL pipes
and fittings (DN 60 to 600), their field of use being similar. If the environment is extremely corrosive (sea inlet crossings, marshes, saline ground waters etc.), complete insulation of the main is essential, restricted to the high corrosion area. PAM technical teams carry out soil surveys at customers’ request, in order to recommend the most suitable protection.
In order to make the installation easier, provides the polyethylene sleeving in precut lengths.
EN 545: Ductile iron pipes, fittings, accessories and their joints for water pipelines requirements and test methods.
ISO 8180: Ductile iron pipes - Polyethylene sleeving.